Locusts are grasshoppers in the family Acrididae. Many people associate them with the Biblical plague of insects chronicled in Exodus, but modern-day locusts do a fair amount of damage as well. Fortunately for farmers, they will only swarm under certain conditions, and many of these insects live out peaceful, calm lives with no similarities to their infamous Biblical ancestors.
Like other grasshoppers, locusts have powerful hind legs that are designed for jumping. They are also capable of producing musical sounds with their wings and hind legs, and they have distinctive short antennae. This last trait has led some people to call locusts “short horned grasshoppers.” When the insect lays eggs, it buries them in the ground; as the eggs hatch, a larval form called a nymph emerges. Nymphs slowly mature into adults to repeat the cycle of reproduction.
Under most circumstances, locusts live out relatively solitary lives, questing for food, laying eggs, and then quietly dying. However, when locusts are subjected to overcrowding as nymphs, they develop into gregarious migratory adults. This evolutionary response was probably designed to ensure that the young had a chance at survival by encouraging them to venture far afield, but groups of these insects have been having a devastating effect on human crops for thousands of years.
When locusts swarm, they can eat their own body weight in food every day. They gather in huge groups that can literally darken the sky and strip fields bare. There is little to be done when combating a modern-day plague of locusts; many farmers burn green branches to create smoke in the hopes of driving the insects out, but this technique is not always effective. Predatory species are sometimes used to control locusts, along with chemical solutions like insecticides, but none of these methods are foolproof. In an astoundingly short period of time, they can completely destroy a crop; irritating for commercial agriculture, but life-threatening for subsistence farmers.
These interesting grasshoppers have been a frequent subject of study for biologists and scientists. Their unusual swarming behavior has been extensively studied in the hopes of understanding and perhaps preventing devastating swarms. One of the most infamous is the desert locust, Schistocerca gregaria, which plagues much of Africa, Asia, and the Middle East in huge swarms that can travel over immense distances, causing severe damage.